DEPRECATED: There is now an easier and better way to bring back those buttons: https://www.xda-developers.com/bring-back-wifi-mobile-data-quick-settings-tiles-android-12-adb/ Just execute in adb shell:
settings put global settings_provider_model false
settings put secure sysui_qs_tiles "wifi,cell,$(settings get secure sysui_qs_tiles)"
Google has removed Wi-Fi from QS in Android 12 replacing it with useless Internet button This tiny project brings it back
Target API 28 is required to allow this app to turn Wi-Fi on and off. Location permission is optional, if you want to show connected Wi-Fi SSID and currently must be granted manually.
I can't publish this in Google Play, since it requires minimum target API 29. It's possible to use higher API if user grants this app a Device Admin role. Not implemented currently, but I may do that in spare time.